Ionic liquids are essentially salts in a liquid state, and are described in U.S. Pat. No. 4,764,440, U.S. Pat. No. 5,104,840, and U.S. Pat. No. 5,824,832. The properties vary extensively for different ionic liquids, and the use of ionic liquids depends on the properties of a given ionic liquid. Depending on the organic cation of the ionic liquid and the anion, the ionic liquid can have very different properties. The behavior of the ionic liquid varies considerably for different temperature ranges, and it is preferred to find ionic liquids that do not require operation under more extreme conditions such as refrigeration.
Acidic ionic liquid may be used as a catalyst in various chemical reactions, such as for the alkylation of iso-butane with olefins. The alkylation reaction is highly exothermic. To control the temperature, it is common for a portion of the unreacted lighter hydrocarbons to be vaporized. However, controlling the heat by vaporization is undesirable because the vaporization creates difficulties in controlling the reactor operation, the ionic liquid dispersion, and, the acid concentration. Therefore, it is believed to be more desirable to maintain the reactants and products in liquid form.
While it would be desirable to utilize heat exchange to control the temperature, any heat exchanger will need to be configured for minimizing the impact of the ionic liquid phase on heat transfer due to its high viscosity and potential for fouling of the heat transfer surface.
Additionally, as will be appreciated, conjunct polymer is often a byproduct of the various ionic liquid catalyst reactions including but not limited to alkylation, oligomerization, isomerization, and disproportionation. Conjunct polymer is typically highly conjugated, olefinic, highly cyclic hydrocarbons. The conjunct polymer is often associated with ionic liquid and will also impact heat transfer in similar ways as ionic liquid.
It would be desirable to provide an ionic liquid reactor that can effectively control the heat produced by exothermic reactions without the need of vaporization. It would also be desirable for such a reactor to account for the presence of conjunct polymer and ionic liquid catalyst.